docs: def tarzip_data(root_dir, output_file):
      """
      Given a root directory, adds all its children to a tarball (compressed)
      :param root_dir:
      :param output_file:
      :return:
      """
      if root_dir is None:
          raise ValueError('Must be a valid directory path', root_dir)
  
      t = tarfile.open(output_file, 'w:gz')
      for child in os.listdir(root_dir):
          t.add(os.path.join(root_dir,child), arcname=child)
      t.close()
      return t.name